Why is that crab waving at me?


The big picture: Animal behavior





  • Behavior: an action carried out by muscles under control of the nervous system
    • works via sensory pathway in nervous systems


  • Behaviors have a genetic basis
    • allows for evolution by natural selection


  • Learning connects experience and behavior
    • Genetics x Environment

Niko Tinbergen: Understanding animal behavior…




  • Q1. What stimulus elicits the behavior, and what physiological mechanisms bring about the response?


  • Q2. How does the animal’s experience during growth and development influence the response?


  • Q3. How does the behavior aid survival and reproduction?


  • Q4. What is the behavior’s evolutionary history?


Take home message: Behaviors are not just a spontaneous reaction to a stimulus

Fixed action patterns



  • Q1: what stimuli trigger behaviors…
    • Tinbergen kept fish tanks with stickleback fish
    • Males = red belly; Females= no red belly


  • Male territorial behavior related to red color
    • males also behaved aggressively when a red truck passed by!


  • What mechanism regulates the response…?
    • Fixed Action Pattern:
    • developmentally ‘fixed’ → innate behavior
    • trigger = specific stimulus (i.e. red color)

Environmental cues for behavior: Migration




  • Environmental stimuli trigger and guide animal behaviors
    • for innate and learned behaviors


  • Birds, fishes, mammals (+ more) use cues to migrate long distances
    • Why do animals not get lost in new habitats?


  • Animals may use sun or moon position or gravitational fields to navigate
    • adjust routes with circadian clocks!

Pigeon Returning Home: What happens if it is cloudy?


Rhythm is gonna get you




  • Animal behaviors also reflect biological rhythms (Q1)
    • circadian clocks or longer cycles


  • Migration and reproduction cued by seasonal cycles
    • periods of day length or temperature cues


  • Behaviors rhythms can be related to lunar cycles
    • includes tides (e.g. crab reproduction, turtle nesting)

Forms of animal communication




  • Stimuli may come from other animals (Q1)


  • Signal: a variety of mechanisms to communicate
    • male waving claw at female crab


  • Communication: transmission and reception of signals
    • plays a role in primary cause (‘the How’)


  • 4 common modes of animal communication
    • visual, chemical, tactile & auditory

Fruit fly courtship use all 4 modes of communication



  • Step 1: Male sees female and orients towards her
    • uses olfactory chemical system to determine species


  • Step 2: Male touches female with foreleg
    • alerts female to his presence


  • Step 3: Male vibrate wing in courtship song
    • auditory behaviors shows female he is ‘fit’


  • If all communications are successful → sexy time

https://www.youtube.com/watch?v=KzWIuhXMUko


Forms of communication evolve with animal’s environment


  • Many terrestrial mammals are nocturnal
    • use olfactory and auditory forms
    • usually are color blind


  • Humans and most birds are diurnal
    • use visual and auditory forms
    • lack many olfactory cues


  • The amount of information communicated varies
    • Bees communicate flower location using special dances. One bee dances, while other bees watch to learn the directions to a specific flower patch. The dancing bee smells like the flower patch, and also gives the watching bees a taste of the nectar she gathered. Smell and taste helps other bees find the correct flower patch.

Experience and behavior


  • Q2: How does the animal’s experience during growth and development influence behavior?


  • What behaviors are innate and what are learned?
    • cross-fostering & human twin studies

The capacity to learn in the animal kingdom



  • Learning: Modifications of behaviors as a result of experience


  • Learning capacity → nervous system organization during development
    • genome encoded (behavior exists)


  • Both nature (genes) vs nurture (environment)
    • finches can sing, but learn song from father


  • Learning Types: Imprinting, Spatial, Associative, Cognitive, Social

Landmarks (Spatial) + Trial and Error (Associative)


Trouble with assembling IKEA furniture? Call a crow…


Cognitive learning = problem solving through experimentation

Social learning in animals: root of culture


Evolution of foraging (Tinbergen Q3: Why?)



  • Q3: How does the behavior aid survival and reproduction?


  • Food related behaviors: eating, searching, recognizing & capture
    • how did foraging behavior evolve?


  • Fruit flies: variation in a ‘foraging’ gene (for) dictates larval travel when foraging
    • forR (rover) vs forS (sitter)


  • Which allele will be selected for in any population?

Evolution of mate choice (Tinbergen Q3: Why?)



  • Mate choice and mating behavior influence reproductive success


  • Seeking, attracting & choosing mates are all under selection
    • creates mate competition


  • Evolution of parental care produces more viable offspring
    • monogamy vs polygamy
    • certainty of paternity


  • Mate choice behavior leads to sexual and intrasexual selection

How have behaviors evolved (Tinbergen Q4)




  • Behaviors have a genetic basis over the history of the species


  • Fruit fly courtship: series of behaviors in male flies
    • single gene (flu) controls entire ritual
    • if flu mutated → no mating
    • variation in gene → variation in behavior
    • e.g., roles can be reversed in male and female!!!


  • Variation in environment may cause behavior to evolve

Are all behaviors evolved to be selfish?



  • Behaviors should be mostly selfish
    • individual vs competitors


  • Altruism: selfless concern for others…
    • sterile bees?
    • animals that vocalize warning calls?


  • Can unselfishness arise through natural selection?
    • offspring survival: yours and relatives


  • Inclusive fitness: increases genetic representation of related offspring…